1. Field of the Invention
This invention relates to the field of art of circuitry for sensing the output of memory cells in CMOS memories. Specifically, the circuit of this invention relates to sensing either a high or a low output from a memory cell, performing level shifting and linear amplification, and transferring the information in the memory cell to other circuits for communication to external pins.
2. BACKGROUND ART
When a CMOS memory cell is accessed the output, either a high voltage level or a low voltage level, will be sensed and this information will be transferred to an external pin. The larger the swing between this high level and this low level, the more reliably it can be determined whether a one or a zero was stored in that cell. However, larger swings require more time and cause a greater power dissipation due to the higher charge flow.
CMOS memories contain supply rails which distribute the supply voltage throughtout the chip. The difference in voltage levels between a one and a zero stored in a memory cell is seen as a swing from the voltage supply rail. Thus, the closer to the voltage of the supply rail that a sense amplifier can operate, the faster the memory circuit can be.
It is thus the object of this invention to sense extremely small voltage swings substantially at or very close to the voltage supply rail, level shift it to approximately one-half of the rail voltage, and perform linear amplification upon this signal.